Serpentinous structure in the right atrium.

Thin, slender, filament like structure is common finding in right atrium echocardiographically. These structures generally represent embryological remnants like thebasian valve, eustachian valve and chiari network. Apart from these variants, they can also be initial finding of thrombotic process specially in the presence of central venous catheter. Early detection and removing the catheter can prevent further thromboembolism in such cases.

A 58-year-old gentleman with history of chronic kidney disease (CKD) was admitted with shortness of breath on mild routine activities. A double-lumen dialysis central venous catheter (CVC) was inserted through the right internal jugular vein (IJV) for hemodialysis. On the 8th day of admission, the patient underwent coronary angiography due to chest discomfort. It revealed triple-vessel coronary artery disease. Transthoracic echocardiographic window examination was poor due to obesity, and details of examination could not be evaluated except for normal left ventricle function with no valvular lesions. The patient underwent uneventful off-pump coronary artery bypass surgery. Six hours after the surgery, hemodynamics started deteriorating. Transesophageal echocardiographic (TEE) examination was suggestive of good ventricular contractility but underfilled chambers. Fluid resuscitation stabilized the hemodynamics. Comprehensive TEE examination also revealed that freely mobile, floating, slender structure was observed in the right atrium (RA) [Figure 1 and Video Clip 1]. What is the diagnosis? The diagnosis is elongated thrombus.

Figure 1

Mid-esophageal bicaval (left) and modified bicaval (right) echocardiographic view showing serpentinous structure in the right atrium

Mid-esophageal bicaval view was suggestive of whip-like structure floating in RA [Video Clip 1]. This structure was extending from superior vena cava (SVC) as seen upper esophageal echocardiographic view [Figure 2 and Video Clips 2, 3]. Differential diagnoses in such cases are generally anatomical variants in RA such as Chiari network, eustachian valve, Thebesian valve. Eustachian valve is attached to inferior vena cava (IVC) opening into RA and Thebesian valve guards the coronary sinus. The Chiari network forms elongated and fenestrated echogenic structure originating from either the Thebesian or eustachian valve and is attached to the wall of the RA or the interatrial septum. However, the mobile structure in the present case neither originated from IVC or coronary sinus nor is attached with eustachian or Thebesian valve [Video Clip 4]. Migrating free thrombi in the RA are generally noticed as mobile, snake-like structure and can be easily confused with the Chiari network. However, such thrombi are thicker than the Chiari network. Extension of this structure in SVC was suggestive of its extracardiac origin. It was considered to be thrombotic slender mass possibly attached to dialysis catheter. The catheter was removed, and small thrombus was noticed attached to side port of the catheter. However, TEE was still showing the same free-floating slender thrombotic mass in RA from SVC. The thrombus possibly has been attached with venous wall or IJV valve. CVC in IJV has been reported to carry approximately four-fold higher risk of thrombus formation than the subclavian vein.[1] Vessel wall trauma and venous intimal hyperplasia by central venous catheterization are possible pathways to thrombogenesis.[2] Insertion of guidewire of the catheter can potentially damage IJV valve which can initiate thrombotic process. Such risk is elevated in the presence of the catheter with large diameter as in the present case.[3] Moreover, the patients with CKD are generally at risk of venous thromboembolism due to raised fibrinogen, increased platelet activation and aggregation, and endothelial cell dysfunction.[4] The patient was started on anticoagulant postoperatively and did not have any other significant events after that. Computed tomography could have delineated the origin of the structure, but it was not done in the present case.

Figure 2

Mid-esophageal bicaval view (left) showing elongated thrombus coming from superior vena cava; mid-esophageal short axis view (right) showing thrombus and dialysis catheter

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